Have a go with Tungsten Carbide (if you're not already)

[Magic9r]

If you're considering giving Tungsten Carbide tools a go I suggest that this is a very good idea.

My reasoning behind this is that nearly everything I've done with carbide, both indexable and solid tools has been covered on the Internet as difficult, impossible or inadvisable for the HSM, there's a lot of complete rubbish coming from aparently experienced machinists

http://s135.photobucket.com/albums/q...t=05fd3c54.flv

is a link to a quick movie I shot as I was taking a 30 thou cut from the case hardened surface of a J&S Clamp Knurling Tool which I am repairing & modifying to fit my Myford Super 7 lathe.

So it's an interrupted cut (3 insert face mill) on a narrow workpiece that has a hardened surface and the cut is being made with a gear head benchtop mill with a 0.12HP 3phase motor running from a single phase fed VFD.

I completed the job & returned the tool to the drawer with three intact, sharp inserts,

I'm getting good results in the mill & on the lathe with 316 SS, Aluminium, Titanium, Tool Steel, Mild Steel and Cast Iron.
For anyone who has not tried one I recommend the ripper style endmills, I've been using my 10 mm ripper for all of the above metals and it's still going strong.

Go on, have a go, there's some bargains in carbide tooling now it's so common in industry,
Regards,
Nick

[Evan]

I use carbide tooling on my SB9 from time to time with difficult materials even though my SB isn't considered as having the power or speed to make good use of it. Recently I was turning a piece of hardened shafting to use as a bearing shaft for the power unit on my picket twister. HSS wouldn't cut it so I switched to carbide. I don't buy carbide tooling or inserts but use various grades of solid carbide that I grind to shape on a slow speed 10" diamond wheel.

In this case I turned the shaft dry at high rpm to the point that the material was sparking. The resulting finish was mirror smooth. I use zero or slightly negative rake.

Carbide has a place in the home shop but in most cases HSS tooling will do the job at at considerably less expense, especially if you must buy preforms. If given the choice between the two when either will do then HSS tools are my choice. It's much cheaper, easier to shape and sharpen and takes a finer edge.

[J Tiers]

The people who say "you can't use it" are assuming you want to use it, or any other cutting tool to the maximum possible economic limit of speed, feed etc.

That's like saying you cannot whittle with a steak knife, you HAVE to use a jack-knife.

In either case, the "other" tool may make some things easy, others more difficult. It may be best suited to certain things.

But, anyone who wants to can go ahead and turn their 4140 pre-hardened with their "perfectly suited to that low power lathe" carbon steel tools.......

Thanks, I'll use carbide for that, even HSS dulls too fast.

[Evan]

But, anyone who wants to can go ahead and turn their 4140 pre-hardened with their "perfectly suited to that low power lathe" carbon steel tools.......

Even carbon steel tools have a place. Nothing takes as sharp an edge as plain old carbon steel tooling. I use it sometimes on aluminum as it gives an excellent finish without much danger of overheating and drawing the temper.

[aboard_epsilon]

http://s135.photobucket.com/albums/q...t=05fd3c54.flv

I wouldn't be doing it like that ..I would have the cutter so that it only just comes over the other side of the work ..

That way you're not knocking the cutting edges twice......AND KNOCKING THE HELL OUT OF THE BEARINGS ON YOUR MILL.. I would be sending the cutter in and arc across the piece .

that's how I've found works best for me anyway ....

In-fact i would not even use a face mill until the work was at least 3/4 of the diameter of it .

you want the cutting front to be as long as possible

yep carbide face mills are OK ...

but found with the carbide endmills ...

you make one little mistake and chip the tooth ...the chip revolves around and smashes all the rest of the teeth, making the cutter scrap.

just my own preferences .....anyone want to say I'm wrong are quite welcome to tell me why and point me in the right direction.


All the best.mark

[J Tiers]

Even carbon steel tools have a place. Nothing takes as sharp an edge as plain old carbon steel tooling. I use it sometimes on aluminum as it gives an excellent finish without much danger of overheating and drawing the temper.

yurp........ Good so long as temps are low

But not so good for straw-blue chips on 4140.........

[Mark Hockett]

yep carbide face mills are OK ...

but found with the carbide endmills ...

you make one little mistake and chip the tooth ...the chip revolves around and smashes all the rest of the teeth, making the cutter scrap.

just my own preferences .....anyone want to say I'm wrong are quite welcome to tell me why and point me in the right direction.


All the best.mark

Mark,
That is absolutely correct about carbide end mills. Carbide EM's will work on a manual mill but will not last very long due to chipping. Carbide EM's don't work as well when cutting in the conventional direction, they work best when climb cutting where the chips are pushed behind the cut and not in front of it. Heavy climb cuts can be difficult on a manual mill due to the backlash.

Idexable carbide tooling is a different animal. It has a much more robust cutting edge and can handle a fair amount of abuse. I have many indexable carbide cutting tools I use on my manual mill.

[Magic9r]

With carbide endmills if you climb-mill there's less tendency for chips to carry around to the cutting edge again, and if you clear the chips with air, vacuum, coolant or even a paint brush it just doesn't happen at all.

I do find that a tip with a larger radius is better for aluminium.

What are you guys paying for inserts? I'm using predominantly triangular, about 10mm on a side and pay under $2 a piece even taking into account the prevailing exchange rate.

I tried the cut with more of a sweep but since cutter 1 leaves the work before cutter 2 hits it it made no difference to tone or loading on the mill, I'd have done the job with an endmill but I was unsure what the depth & hardness of the surface treatment was so I went for this in case it ate a few inserts, better that than a nice endmill. Perhaps I could apply a small friction load to the spindle to keep the geartrain loaded but I don't make a habit of cuts like this one, Honest

I still use some HSS for certain operations like cutting multi-vee pulleys with a hand ground, single point tool, but for straight cuts in the time it would take to sharpen a HSS bit I've rotated the insert and completed the operation. I don't mind sharpening tool tips but it's not why I'm in my workshop.

It may be that my Super 7 is a bit wierd in that the plane nose bearing allows high speed running and this is why I can get the lathe up there where carbide really does it's thing (the 1HP 3PH motor with VFD allows speeds from zero to double the motor's rated rpm) allowing me to go up to around 4000 rpm provided the chuck is rated for that (my 4-jaw isn't).
Regards,
Nick

[BigBoy1]

Every tool has its place and knowing when to use them and not to use them is one of the things experience will provide. I have both HSS and Carbide tools and each has a job it can do. Sometimes they overlap and both can do the job and other times, only one type will work. The big thing is knowing the difference and when to use one over the other.

Bill

[pcarpenter]

I am curious about the notion of a plain (plane?) nose bearing allowing high-speed running. Typically, plain bearings can limit safe high speed running, although 4000 RPM is not that high as spindle speeds go. It's quite high for a lathe spindle, but milling spindles running on very low tolerance ball or roller races are turning ten times that in some special machines. Is the implication that if you had a ball or roller bearing headstock you could not turn that fast?

I use both and prefer carbide for harder stuff as others have said. While carbide does offer the ability to do high-speed machining, that is rarely important to folks using machines in the Super 7 class (home shop types). Usually we are looking for better surface finish and that often comes from the use of HSS. The other big advantage to HSS is that its easy to tweak cutter geometry to improve finish....something that is more limited with insert cutters that require the purchase of a package of fairly standard inserts.

People often labor over grinding a HSS tool. While care in desiging the angles and grinding them is a good idea, resharpening does not need to require regrinding. Often a few strokes of a good stone will bring an edge back up to sharpness. "Sharp" carbide inserts for insert holders are often pretty rare and that can make for more load on a machine as well as for the need for deeper depths of cut. As a home shop type, I often sneak up on a dimension and my last cut may be a few thousandths...which is often less than the ideal depth or chip load for a carbide insert with its chip breaker back a good ways from its leading edge (by design).

Paul